CVE-2022-1011 in Linux
Summary
by MITRE • 03/18/2022
A flaw use after free in the Linux kernel FUSE filesystem was found in the way user triggers write(). A local user could use this flaw to get some unauthorized access to some data from the FUSE filesystem and as result potentially privilege escalation too.
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Analysis
by VulDB Data Team • 04/02/2026
The vulnerability identified as CVE-2022-1011 represents a critical use-after-free flaw within the Linux kernel's FUSE (Filesystem in Userspace) implementation that fundamentally compromises system security boundaries. This issue manifests when a local user triggers the write() system call on FUSE filesystem operations, creating a scenario where freed memory regions are accessed after being deallocated, leading to unpredictable behavior and potential exploitation. The FUSE subsystem allows non-privileged users to create custom filesystems in user space, making it a critical component in system architecture that bridges kernel and user space operations.
The technical exploitation of this vulnerability stems from improper memory management within the kernel's FUSE driver where a user-space process can manipulate filesystem operations to cause a specific memory region to be freed while still being referenced by subsequent operations. This memory corruption occurs during write operations when the kernel fails to properly validate or manage the lifecycle of memory allocations associated with FUSE filesystem handles. The flaw resides in the kernel's handling of file operations within the FUSE subsystem, specifically in how the kernel manages the reference counting and deallocation of filesystem objects during write operations.
From an operational perspective, this vulnerability creates a significant attack surface for local users to potentially escalate privileges and access unauthorized data within the FUSE filesystem. The use-after-free condition allows an attacker to manipulate memory contents in ways that could lead to arbitrary code execution within kernel space, enabling privilege escalation from user-level to kernel-level access. This represents a severe security risk because FUSE filesystems are often used for legitimate system functions and user-space filesystem implementations, making the exploitation vector both widespread and impactful. The vulnerability's local nature means that an attacker must already have access to the system, but the potential for privilege escalation makes it particularly dangerous in multi-user environments.
The security implications extend beyond simple data access as this vulnerability aligns with common attack patterns documented in the ATT&CK framework under privilege escalation techniques and kernel exploitation methods. This flaw directly relates to CWE-416 which describes the use-after-free vulnerability pattern, and the exploitation process follows typical kernel exploitation methodologies where memory corruption leads to privilege escalation. Organizations using FUSE filesystems, including those implementing custom filesystems or using standard FUSE-based solutions like sshfs, rclone, or various cloud storage integrations, face elevated risk. The vulnerability affects all Linux kernel versions that include FUSE support, making it a widespread concern across enterprise and consumer systems that rely on FUSE-based filesystem implementations for various operational requirements.
Mitigation strategies for CVE-2022-1011 primarily focus on immediate kernel updates and patches provided by Linux kernel maintainers, as this vulnerability requires kernel-level fixes to address the underlying memory management issues. System administrators should prioritize patching affected systems, particularly those running kernel versions that include FUSE support. Additionally, implementing strict access controls and monitoring for unusual FUSE filesystem operations can help detect potential exploitation attempts. The vulnerability demonstrates the importance of proper memory management in kernel space and highlights the need for comprehensive testing of filesystem operations, especially those involving user-space interactions. Organizations should also consider implementing kernel hardening measures such as stack canaries, address space layout randomization, and kernel module signing to reduce the effectiveness of potential exploitation attempts. Regular security audits of FUSE-based filesystem implementations and monitoring of system logs for unusual filesystem activity can provide early detection of exploitation attempts.